How to Traumatize Your Parents
by LeelaSmall
Summary: After Dipper accidentally tells his parents about his sister's relationship with Bill, Mabel has no choice but to introduce them to the demon and their daughter. The question is... exactly HOW is she going to do that? Set shortly after Lullaby. Requested by GamerFan369.
1. Crying Over Spilt Beans

"That'll be $49,99."

Mabel extended her arm as her customer took out two twenties and a ten, slapping them down on the brunette's hand as she told her to keep the change and hurriedly exited the boutique with her newly purchased clothes, without uttering as much as a 'thank you' or a 'goodbye'.

She didn't mind the attitude; in all honesty, she was already used to it. Gravity Falls was a really small town and people would get sick of each other easily and act out towards one another. Thankfully, there were still some who actually bothered to be polite towards her and others. She always enjoyed when they came in, sometimes just to say hi to her.

She hummed a happy tune to herself as she stored the money away in the register drawer and closed it, leaning over the counter as she inspected the inside of her small store. There weren't many customers inside at the moment, probably because it was close to lunch time, and those who were there seemed to be browsing mindlessly through the many articles of clothing in hopes of finding something good. She liked to keep an eye on her customers as they roamed around, having suffered a theft or two in the past. Sure, they had installed security cameras after that, but she always liked to stay alert.

Making sure everything was within normality, Mabel nodded to herself and picked up a box of unfolded sweaters from underneath the counter, which she began to fold neatly one by one. She wanted to have done that as soon as she opened the store earlier, but she had an unusual amount of customers in the morning that kept from getting much done.

 _Nice to meet you!_

 _My name is Dipper Pines_

 _P-P-Pines, Pines, Pines…_

She muffled a giggle as she glanced down at the picture of her brother on her phone's screen, noticing from the corner of her eye that some of the customers had curiously looked up at her due to the odd ringtone. She quickly picked up the smartphone from the counter and slid her finger across the screen to answer the call, trying to keep herself from laughing at the strange looks she was getting as she brought the device up to her ear.

"Hey bro, whaddya know?" she greeted her twin, holding her phone with her shoulder so she could keep folding the clothes.

"H-hey, Mabes!" Dipper chuckled, sounding ratter nervous. "How've you been?"

"Is everything OK, Dipper? You sound kind of on edge."

"Wha-what?" he laughed forcedly, unable to hide the uneasiness in his voice. "What g-gave you that idea?"

"I haven't heard you stutter this much since that time you had to tell dad you crashed his car on the way back from senior prom." She stated, a small smirk appearing on her lips from the memory. "What did you do this time?"

"Alright…" he sighed. "But before I begin, please have in mind that this was an accident."

"Trust me, bro-bro, whatever you did can't possibly shock me." She giggled as she smoothed some creases on one of the sweaters she was folding. "Not after all the crazy stuff we've seen and done over the years."

"I accidentally told mom about Bill."

The thick sweater escaped Mabel's slender fingers as she suddenly felt like she had lost all the strength she needed to hold it, along with her ability to breathe. Her eyes almost popped out of her skull and she could feel her heart pounding like a jackhammer against her chest as she processed what she had just heard.

"You WHAT?!" she shouted at the top of her lungs, making some of her customers jump and look up at her worriedly.

Mabel quickly took her phone from between her shoulder and her ear and turned around, her cheeks feeling incredibly warm.

"Dipper, how could you do that?!" she whisper-shouted into her phone, trying to steady her breathing. "Mom and dad were never supposed to find out about him!"

"I know, and I'm really sorry! Mom called me and she was asking how Pacifica was and telling me how much she liked her and how she wished you could find someone who could make you as happy as she makes me, and then…" he paused, a long sigh emanating from the other side. "I'm still not sure how it happened, but before I knew it I was telling her about how happy you were with Bill. I'm really sorry, I can't believe I just let it slip out like that!"

"What am I supposed to do now?" Mabel whined, burying her face in her free hand. "Mom's gonna call me any minute and ask a million questions on the matter. And I can't just tell her the truth! It would destroy her!"

"I don't know, Mabel. Maybe it's time mom and dad found out what's been going on in your life."

"Oh, really?" she scoffed. "Then I guess I'll just call her myself and say 'Hey mom, how's it hangin'? Oh, by the way, I'm dating a demon and he got me pregnant last year, so now you're the proud grandmother of a half-demon baby girl'! ARE YOU OUT OF YOUR MIND RIGHT NOW?!"

"Mabel, calm down!" Dipper exclaimed, sounding almost as panicked as her. "I'm sure we can think of something."

Mabel opened her mouth to reply, but quickly shut it when she heard the beeping sound of an incoming call coming from her phone. She felt her heart sink when she brought her phone down and looked at the screen, where she saw a picture of her mother. She swallowed the lump forming in her throat before taking the phone back up to her ear.

"Mom's calling me." She whimpered, her mouth suddenly feeling incredibly dry. "What do I do?"

"Try to stay calm. And don't worry. You're a grown woman, so they can't punish you for your choices anymore. Plus, I really think it's time they finally knew the truth."

"OK, I'll try." Mabel sighed as she began to think about what she was going to say. "If you don't hear back from me in thirty minutes, I probably moved to another dimension. I heard Mewni is pretty nice this time of year."

"Alright." Dipper chuckled lightly. "Good luck."

"Thanks, bro-bro."

As soon as she heard her brother hang up, her nerves returned at full throttle. She stared at her mother's picture on the screen, her thumb hovering indecisively over the green 'answer call' icon. She actually considered ignoring it, but she knew her mother wouldn't stop pestering her until she answered her calls. Taking a deep breath, she finally lowered her thumb and accepted the call, her hand shaking as she took the phone up to her ear again.

"H-hi, mom…"

* * *

"The little boy then opened the box to reveal what looked like a doll's severed arm. He seemed confused by why he had received such a gift, but all that is forgotten when the arm latched onto his neck, and he heard his father's maniacal laugh as everything went black. The end."

Bill Cipher gently closed the book in his hands as he glanced towards the black wooden crib before him, where his half-demon baby girl was sleeping soundly. A wide grin spread across the humanized dream demon's face as he stood up from his seat and made his way towards his snoozing daughter, watching her squirm slightly as he pulled her blanket over her shoulders.

"Pleasant nightmares, my little devil princess." He whispered, gently brushing her tiny purple locks. "I can't wait until you're old enough to show me your true potential."

The blond released a long sigh as he observed her chest rise and fall with each breath, but jolted when he suddenly heard the front door slam open and then close just as loudly. He heard a female voice groan audibly from downstairs, a voice he had heard a lot over the years.

"BIIIIIIIIIIIIIIIIIIIIIIIIIIILLLLLLLLL…" she whined almost desperately, bringing a sympathetic smile to his face.

"Looks like mommy's home." He declared, giving his daughter's hair one last stroke before snapping his fingers and disappearing from Erin's room.

He reappeared in the living room, stifling a chuckle when he saw his girlfriend lying face-down on the couch, still groaning loudly.

"Bad day at work, honey buns?" he asked almost mockingly as he sat on the armrest next to where her head was.

"The worst…" she moaned into the couch cushions beneath her. "Something terrible happened."

"How terrible are talking about?"

"Dipper spilled the beans about us to my mom." She declared, reaching for one of the throw pillows and pressing it against the back of her head.

"Oh. Well, I guess it was bound to happen sooner or later." He shrugged. "Was she mad?"

"Not exactly. She was mostly happy that I'm finally in a relationship."

"Really? You'd think she would be furious that you're dating a demon whom you had a child with."

Mabel didn't reply; she simply remained silent after that remark. Bill frowned when he realized what her silence meant.

"You didn't tell her, did you?" he deadpanned as he furrowed his brow.

"I couldn't!" she exclaimed, lifting her head to meet his gaze. "How could I explain all that to my mom? She would be devastated!"

"I see how it is." He murmured as he crossed his arms. "You're ashamed of me."

"Of course not!" she quickly sat up and placed a hand on Bill's shoulder. "I could never be ashamed of you."

"Then why is it so hard to tell you mother the truth about me and your daughter?"

"Because they would never accept it! Worst of all, they would never accept _you_! How would you feel if you had to tell your parents that you're romantically involved with a human?"

"I don't have parents. I was created thousands of years ago along with the Earth itself."

"But imagine if you _did_ have parents. Do you think it would be easy to tell them about me?"

Bill tapped his chin as he imagined that scenario, realization dawning on him after just a couple of seconds.

"Ohhh…" he said, his eye widening slightly. "I get it."

"Thank you." She sighed, slumping against the couch.

"But you can't hide us forever. What if they want to come visit some day?"

"Oh, yeah… about that…" She giggled nervously, lightly tugging at her hair. "They've invited themselves over for dinner tomorrow."

"WHAT?!" Bill shouted. "And you allowed it?!"

"I couldn't just say no! They're my parents!"

"Alright…" Bill sighed as he pinched the bridge of his nose to calm himself down. "I can see there's only one way out of this." He extended his index finger upwards, a small blue flame appearing on the tip.

"Bill Cipher! You're not seriously thinking about killing my parents, are you?" Mabel inquired in outrage.

"Actually, I was just planning to burn the house down and fake our own deaths." He stated before blowing out the flame.

"That's terrible! Besides, I have a better idea."

* * *

 **AUTHOR'S NOTE (PLEASE READ)**

 ***Eddy Murphy's voice* I LIIIIIIIIIIVE!**

 **Wow, it sure has been a while, hasn't it? I'm sorry I didn't update sooner, but I've been really busy. Those of you who follow me on Twitter and/or Tumblr know what's been going on in my life, what with me taking my college acceptance exams and then applying last week.**

 **Anyways, about this fic. I was planning for it to be a one-shot, but then I realized it was going to turn out really long, so I'm dividing it into two chapters. Also, as always, I'll be taking suggestions from you guys! If you have any good ideas about how make the encounter between Bill and Mabel's parents funnier and more interesting, don't hesitate to throw them my way! ;D**


	2. What Could Possibly Go Wrong?

_Ding dong!_

"THEY'RE HERE!"

Mabel almost tripped over her own feet as she hurried towards the door, feeling her hands shake like leaves as she reached for the doorknob. She couldn't remember the last time she had been so nervous. This night had to go without a hitch, or else… She didn't even want to think about what could happen if something went wrong.

Trying her best to calm her beating heart as she adjusted her clothes for the umpteenth time, she turned the knob and pulled back the door, immediately grinning at the sight of her smiling parents.

"Hi mom, hi dad!" she greeted them, trying her best not give her nerves away in her tone.

"Oh honey, I missed you so much!" Mrs. Pines exclaimed as she wrapped her arms around her daughter, squeezing her tightly. "It feels like forever since we last saw you!"

"It's only been two years." Mabel replied as she returned her mother's embrace.

"You know your mother can't stay away from you or your brother for too long." Mr. Pines added, moving forward to join the hug. "You have no idea how long it took me to cheer her up after you went away for college."

"Oh please, I wasn't that depressed!"

"I came home from work one day to find you lying in bed bawling with the kids' baby pictures all over you." He deadpanned.

"That was different! I was menopausing!" Mrs. Pines refuted as she released her daughter. "My hormones were in overdrive!"

"Sure they were…" Mr. Pines chuckled, rolling his eyes.

"Oh hush, we didn't come all this way to talk about my nervous breakdowns. We're here to meet the young man who's been taking such good care of our little girl!" she squealed, playfully squeezing her daughter's rosy cheeks. "So where is this boyfriend of yours?"

"Oh, Bill?" Mabel asked involuntarily. "He's – "

"Right here."

Mabel immediately whipped her head around at the sound of the demon's voice, her eyes widening upon the sight. She was used to seeing the blond dressed in the same formal outfit every day, but that evening he had opted to don a pale-yellow dress shirt tucked into a pair of black slacks and a pair black loafers. His hair had been neatly combed back and his triangular eyepatch over his right eye had been replaced with a simple medical patch. Save for that aspect, he looked about as normal as could be.

"Mr. and Mrs. Pines, it's so nice to finally meet you!" he said as he moved towards them with his arms wide open and a bright grin across his face. "Mabel's told me so much about you!"

"My, such a polite young man! And handsome, too!" Mrs. Pines commented, lightly nudging her daughter.

"Thank you, Mrs. Pines. And may I say, you don't look a day over thirty." He replied as he took her hand in his and kissed it. "Now I know where Mabel gets her looks."

"Oh ho ho, my!" she giggled as her cheeks turned red. "Thank you so much, Bill! And please, call me Caskey."

"My pleasure, Caskey." He purred, wiggling his eyebrows at the middle-aged woman before extending his hand to her husband. "And you must be Robert! Mind if I call you Rob? Or maybe Bob? Bobby? Bobert? Bobzilla?"

"Just Robert is fine." He replied drily, reluctantly taking the blond's hand and shaking it. "What's wrong with your eye?"

"Oh, this?" Bill inquired, gently brushing his fingertips against the patch. "I had a bad case of pinkeye a few days ago which lead to a nasty infection. My doctor prescribed me some eye drops and told me to just let it air out, but when I learned that you two were coming over for dinner I ran to the pharmacy and bought some patches to hide it. After all, I wouldn't want to ruin our evening with such a terrible sight."

"Oh, you're absolutely delightful!" Caskey exclaimed. "Mabel, I think you might've hit the jackpot with this one!"

"Yup, I sure did!" Mabel giggled nervously.

"Now, why don't you head to the dining room while I take your coats up to our room?" Bill suggested as he extended his arms forward.

"Thank you, dear!" said Caskey as she took off her coat and handed it to Bill. "I can't believe how hungry I am."

She made her way past the blond as her husband gave him his coat without saying a thing, yet shooting him a rather menacing glare. Bill kept his wide grin as he watched Mabel's parents enter the dining room, releasing a long relieved sigh once they were gone.

"Man, being nice is hard!" he complained, teleporting the coats somewhere else. "How do people manage to do this on a daily basis?"

"You're doing great." Mabel encouraged him, affectionately rubbing his arm. "Keep it up, they love you!"

"No, your mom loves me. Your dad hates my guts."

"He doesn't hate you. He just acts this way every time I introduce him to a new boyfriend of mine." She replied as she moved in closer. "Did you take care of… upstairs?"

"Not to worry, I soundproofed Erin's room with the best spell I know. I guarantee she won't be bothering us tonight."

Meanwhile, up her room, Erin tossed and turned uncomfortably in her crib until she opened her eyes and started to cry, knowing someone would be up shortly to tend to her needs. When that didn't happen she tried crying louder, again with no result. Sick of waiting and forcing her vocal chords, she lifted herself up and crawled over to the bars. She reached for the edge and pulled herself over it, falling flat on the floor with a thud. Ignoring the pain, she crawled towards the door and pushed herself up upon reaching it. She wobbled a bit for a minute but quickly steadied herself, and attempted to reach for the doorknob, which was too high up for her tiny hands to grasp. She jumped a few times in an attempt to catch it, but ended up falling backwards.

She began to feel anger bubble up inside her, which made something unusual happen: her left eye began to glow bright red and she began to slowly levitate upwards. She quickly reached the doorknob, turned it and opened the door, afterwards floating out of the room and down the stairs with surprising ease.

* * *

"So after I majored in Archeology, the only good enough job I could find was at the local library. And let's face it, the way the economy is these days, I couldn't really afford to be too picky about that."

Caskey laughed loudly at the story Bill was telling as he poured is possible future in-laws some wine, while Robert just grunted unamusingly and Mabel grinned widely in a forced attempted to hide her nerves.

"Then one day I was invited to a librarians' seminar at an art school in San Francisco, to which I arrived early so I could tour the vicinity, when I happened to bump into your daughter." He declared as he sat down, turning to gaze lovingly at the brunette on his left. "I had never believed in love at first sight, but that moment completely changed my mind."

"Awwww!" Caskey cooed. "That's so sweet!"

"Yeah…" Mabel giggled nervously as Bill wrapped an arm around her shoulders. "And it's exactly as I remember it."

"I gotta tell you, sweetie, I'm so glad you found such a great guy for yourself." Caskey commented before taking a sip from her wine glass. "After all the crazy things your brother's told us about this whacky town, I was afraid you would end up dating a warlock or something. Oh, you should've heard him talk about this floating one-eyed triangle thing he claimed to be a demon. That's gotta the most ridiculous thing I've ever heard!"

She burst into laughter, nearly spilling the drink in her hand, as the young couple before her released some forced chuckles. Mabel noticed Bill's eye twitch, desperately hoping he wasn't reaching his limit.

Mabel picked up her glass and started swirling it in an attempt to distract herself from her own nervous energy, when she saw something on the surface of the glass that almost made her heart stop: she saw the reflection of the end of the stairs, and her daughter slowly floating down them.

"BILL!" she shouted, rapidly sanding up and grabbing her boyfriend's arm. "The, uh… roast must be almost done! We should check on it! NOW!"

She pulled the blond up and dragged him out the room and towards the staircase, ignoring his words of protest.

"H-hey, what gives?" he asked. "I had them right where I – WHOA!"

Upon reaching the staircase, he finally saw his half-demon baby girl hovering in the air at the bottom of the stairs.

"Erin… you're floating!" he exclaimed in glee as he took his daughter into his arms and hugged her tight. "I'm so proud!"

"Quiet, they'll hear you!" Mabel whispered, slapping a hand over Bill's mouth. "We need to get her back to her room before my parents see her."

"Alright, I'll take her up." He declared before snapping his fingers and disappearing with the baby.

Mabel took a deep breath and recomposed herself as she walked back into the dining room, giving her parents her brightest smile.

"Bill will be right back with the roast." She said as she sat back down. "It was a little dry, so he's basting it."

"It must be quite a good roast, judging by the way you ran out to check on it." Caskey remarked.

"Yup, it's pretty great." Mabel giggled.

"Mabel, I think I speak for both your dad and myself when I say that we're proud of you for finding such a fine gentleman for yourself." She stated, elbowing her husband hard on the ribs. "Right, Robert?"

"Uh, yeah, sure." He muttered as he rubbed his side. "I guess Bill isn't that bad…"

"Wow… thanks, dad." Mabel grinned, feeling at ease for the first time that night. "You have no idea how much that means to – "

Before Mabel could finish her sentence, she was interrupted by the sudden appearance of her purple-haired one-eyed half-demon baby on top of the dining room table. She didn't know what shocked her most: the fact that Erin was right in front of her parents, or the fact that she teleported there.

Erin seemed confused at first, especially when she found herself staring right at her grandparents, whom she had never seen before. Caskey and Robert looked absolutely flabbergasted with the sight of such an unusual-looking infant. Especially due to the fact that she had just appeared out of nowhere.

And to make matters even worse, that's when Bill decided to pop into the room as well.

"She got away from me before I could do anything!" Bill panted as he frantically looked around. "Where did – "

He trailed off when he noticed his surroundings. In his haste he didn't check exactly where his daughter had teleported to before chasing after her. Now, like his mortified girlfriend, he just wished he could find the deepest hole possible and jump into it.

"Heh… would you believe me if I told you that I'm also Houdini's long lost great-grandson?" he chuckled, flashing them his best grin.

Robert and Caskey just kept staring at the three with a dumbfounded expression on their faces. Caskey fainted not long after, falling backwards onto the floor.

"Yeah, I wouldn't believe that, either." Bill sighed in defeat.

* * *

"So let me get this straight…" Caskey began breathlessly, holding an ice bag against the back of her head while her husband just stared at the young couple and the baby Mabel held in her arms. "Bill here is a demon…"

"Yup." Bill confirmed.

"…who got you pregnant with his half-demon spawn…"

"Hm-mh…" Mabel mumbled sadly.

"…and you've kept all this hidden from us during all this time?!"

This time they didn't even bother to say anything; Mabel just sank in her chair and Bill wrapped an arm around her shoulders in a vain attempt to comfort her.

"Well…" Caskey huffed, leaning forward and placing her free hand on her hip. "I cannot believe my own daughter would do such a thing!"

"I'll say." Robert added, a very displeased look upon his face.

"We are very disappointed in you, young lady! I never thought you would even dare to do something like this to us! To be honest, I never thought it was possible, but that's beside the point!"

"I have half a mind to disown you, right now."

"Alright, I've heard enough!" Bill exclaimed, slamming his hands against the table as he stood up. "I spent the whole night acting like the perfect goody-two-shoes exactly because your daughter didn't want something like this to happen. She was terrified about you two finding out the truth because she cares so much about you. That's why she hid all this from you; to protect you!"

"You stay out of this!" Robert interrupted. "You're the reason she's – "

"Can it, _Bob_! I don't care about anything you have to say! The only ones I care about are your daughter and the child we had together!" he continued, gesturing towards Erin, who was now sound asleep in Mabel's lap. "They are the reason I submitted myself to this charade! I would do anything for them! I would do anything for _her_!" he pointed at Mabel. "If you two can't accept that, fine. But you can't keep us apart."

Bill dropped back onto his seat with his arms crossed, refusing to make eye contact with the older couple. Robert and Caskey were silent, presumably in awe from the demon's declarations.

"You… really care about her?" asked Caskey, still quite astonished, to which Bill simply nodded in his infuriated state.

"Mabel… does Bill make you happy?" Robert inquired.

"Yes, he does! I've never been this happy with anyone else in my whole life!" she immediately replied, grabbing Bill's hand and smiling warmly at him. "I love Bill with all my heart, just as I love our daughter and the whole life we built together."

Bill's lips curled upwards into a smile, and Mabel could've sworn she saw a bit of a blush appear on his cheeks.

"Well… than I guess there's nothing we can do about that. You're a grown woman and you're perfectly capable of making your own decisions. Even if those decisions are… rather unusual, we'll just have to learn to live with them." Caskey declared, shooting her husband a stern look. "Right, Robert?"

"Oh, ye-yeah, yeah!" he stammered. "I guess if you're happy, then our work here is done."

"Thanks, guys." Mabel beamed, squeezing Bill's hand. "That means a lot."

"Alright, it's getting pretty late. We should probably head home." Caskey stated as she stood up, placed the ice bag on the table and headed towards her daughter. "We love you, honey. We'll call you when we get home."

"Thanks, mom." She said as she hugged her mother with one arm and held Erin with the other. "I love you, too."

"Oh, before we go, can I hold my granddaughter for just a little bit?"

"Sure! Here you go."

Mabel carefully handed her the snoozing infant, watching as she slowly opened her eyes as she felt a different pair of arms around her.

"You know, for a half-demon baby with just one eye, she's really precious." Caskey declared as she moved her face closer to Erin's. "Hey there, cutie pie! I'm your grandma!"

Upon the sight of the strange woman from earlier so close to her face, Erin began to let out gentle sobs, which then evolved to her usual blood-curling shriek that shattered every window in the house.

"Does that… happen often?" Caskey asked as she handed Erin back to Mabel, her ears now ringing.

"You have no idea." Bill replied.

* * *

 **AUTHOR'S NOTE (PLEASE READ)**

 **Oh my God, I can't believe how long it took me to update this…**

 **I really have to apologize for taking so long with this fic. Those of you who follow me on Twitter and/or Tumblr know what's been going on with my life. Basically… it's been a really awful couple of months.**

 **But anyway, here's the second part, at long last! :D I hope you guys enjoyed it!**

 **And for those of you who noticed, yes, I did use the names of Alex Hirsch's parents as the names for Dipper and Mabel's parents. I thought it was appropriate ^^**

 **Thank you all again for reading this. I will see you next time I post something ;)**

 ***brofist***

 **~LeelaSmall**


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